Instead of just showing app download button, why to ask for mobile no. here is screenshot
There are 2 main reasons this occur, one for the business and the other for the user:
- The company in question gets the users number to use for marketing purposes, to send promotional texts and offers directly to users.
- Its makes it easier and more convenient for the user to download rather than having to search and find it on the app store. Thus increasing conversion (whatever that measurement maybe, downloads, data collation, app store ratings etc).
They could just as easily link to the app store but this is a cleverer way of harvesting data from users by offering a reward in the form of a quick way to get to the app. Then they can potentially get more data via the sign up process.
Its easier to download app via sms than to search for it in the store. Maybe they want to have your phone number also.